Matlab: Changing shapes of PDEG

I have the below function:

    function [x,y] = cardioid2(bs,s) 
    if nargin == 0  
      x = 4; % 4 segments
      return 
    end
    if nargin == 1
        % Outer cardioid
        dl = [  0      pi/2   pi       3*pi/2
              pi/2   pi     3*pi/2   2*pi
              1      1      2        2 % To the left is empty
              0      0      0        0]; % To the right is region 2
        dl = [dl];
        x = dl(:,bs);   
        return 
    end 
    x = zeros(size(s)); 
    y = zeros(size(s)); 
    if numel(bs) == 1 % Does bs need scalar expansion?
        bs = bs*ones(size(s)); % Expand bs
    end
    cbs = find(bs < 3); % Upper half of cardiod
    x(cbs) = (4+0.1*cos(s(cbs))).*cos(s(cbs));
    y(cbs) = (4+0.1*cos(s(cbs))).*sin(s(cbs));
    cbs = find(bs >= 3 & bs <= 4); % Lower half of cardioid
    x(cbs) = 4*cos(s(cbs));
    y(cbs) = 0;
    save('my_parameters.mat')
    end

By running code:

    pdegplot('cardioid2','EdgeLabels','on')

A semicircle with radius of 4 will be generated.

I do not know how would it be possible to to modify the code in a way I can have the radius vary proportional to polar angle (let's say r=1+0.2cos(teta)) where teta is from 0 to pi.

Please if you cannot help at least do not vote down, it will pose me to being blocked.

Answer 1

[Alan Weiss]

I am not sure that I understand what you are asking, but did you see the cardioid3 example from the documentation? It does not make a semicircle, it makes a cardioid, where the radius depends on angle.

Alan Weiss

MATLAB mathematical toolbox documentation